So.
The last time I slung solder at this level was when I built a Heathkit DX-60 with my dad in the early 70's.
I ran across an older Dynaco ST-70 a couple of years ago, refreshed it, and that led to this endeavor.
Edcor XPWR155 & GXE15-8-5K transformers.
Triad C-14X choke & 100uF Tenco motor run.
Stock bill of materials, with the exception of the first cap (33uF) to give me some flexibility in rectifiers.
Settled in on 470 ohm cathode resistors after measuring several options in the circuit.
recorded numbers:
nos 5AR4 & el34s. 400 B+, 30.4 V across the resistor for ~61mA plate current.
If my math is correct, which is no sure thing
nos 5AS4 & 6P3SE (6П3СE). 375 B+ & 26.8 V drop for ~54mA.
Same math caveat.
Case had a bit of "Measure once, cut twice & it's still too small" 🙂
Top plate is from SendCutSend & it worked *fine*, in spite of my less than stellar CAD skills.
All in all, for my first tube amp build ever I am very, very happy.
Enjoying Janos Starker playing the Bach cello suites as I type.
George, thank you very much for a grand design and a quality set of instructions!
The last time I slung solder at this level was when I built a Heathkit DX-60 with my dad in the early 70's.
I ran across an older Dynaco ST-70 a couple of years ago, refreshed it, and that led to this endeavor.
Edcor XPWR155 & GXE15-8-5K transformers.
Triad C-14X choke & 100uF Tenco motor run.
Stock bill of materials, with the exception of the first cap (33uF) to give me some flexibility in rectifiers.
Settled in on 470 ohm cathode resistors after measuring several options in the circuit.
recorded numbers:
nos 5AR4 & el34s. 400 B+, 30.4 V across the resistor for ~61mA plate current.
If my math is correct, which is no sure thing
nos 5AS4 & 6P3SE (6П3СE). 375 B+ & 26.8 V drop for ~54mA.
Same math caveat.
Case had a bit of "Measure once, cut twice & it's still too small" 🙂
Top plate is from SendCutSend & it worked *fine*, in spite of my less than stellar CAD skills.
All in all, for my first tube amp build ever I am very, very happy.
Enjoying Janos Starker playing the Bach cello suites as I type.
George, thank you very much for a grand design and a quality set of instructions!
